Continuous can printing and transfering mechanisms require accurate seating of cans on mandrels preparatory to the printing operation, not only to ensure perfect transfer of the image from the printing blanket to the can but also to prevent contact between the mandrel and the image applicator. Such unwanted contact occurs when the can is improperly seated and when a can is missing and the mandrel is exposed. An electronic sensor is provided to detect faulty seating of a can on its mandrel or absence of a can on each mandrel.
This invention relates to mandrel tripping means whereby a mandrel on which a can is improperly seated or a mandrel without a can is moved out of printing position. The invention also relates to means for blowing an improperly seated can off the mandrel.
The invention is an improvement on prior art malfunction correcting means such as the printing blanket retracting mechanism of U.S. Pat. No. 3,261,281, issued to Ruben J. Hartmeister, and such as the spindle moving mechanism of U.S. Pat. No. 3,766,851, issued to Enn Sirvet et al.